Brouwer uses the assault on Vimy Ridge during World War I to highlight the bravery of both Canadian troops and the animals that served.Little Abigail the carrier pigeon miraculously gets a critical message from a small group under attack back to command. Tomato the border collie navigates the trenches during a gas attack with another critical message. Louise the packhorse carries hundreds of pounds of shells to the front lines for the final, successful barrage. The lives of these and five other animals (a cat, a war horse, a mule, a sniffer dog, and, improbably but historically, a lion) intersect with those of the young men of the 36th Battalion, principally Jake, a white farm boy from Manitoba; Thomas, a Cree boy from Saskatchewan, fresh out of the residential schools; and Charlie, a wealthy and disagreeable white boy from Toronto. Chapter by chapter, Brouwer details the action, highlighting the exploits of one animal in each; at the end of each chapter are brief nonfiction passages that provide factual context. While at times the writing is overwrought and the characterization largely simplistic, the author packs a lot into his schema, touting the superiority of Canada's egalitarian approach to hierarchy while also acknowledging the racism of Canada's policies toward the First Nations. Some of the dialogue, particularly Thomas', is skillfully done and laugh-out-loud funny. A steppingstone to Michael Morpurgo's War Horse (1983) and a worthy introduction to the Great War. (Historical fiction. 9-12) Copyright Kirkus Reviews, used with permission.